a) Field of the Invention
This invention relates to a multiplate clutch, and especially to an attachment structure of a sleeve on a clutch case.
b) Description of the Related Art
FIG. 1 illustrates in a cross-section one example of a basic construction of a multiplate clutch 10. Designated at numeral 1 are separator plates, each of which is not provided with friction linings and is in engagement with a spline 31 on a clutch case 3. Numeral 2 indicates friction plates, each of which carries on both sides thereof friction linings bonded thereon. Numeral 4 designates a piston arranged for actuation by hydraulic pressure and upon engaging the clutch, the piston 4 presses the separator plates 1 and the friction plates 2 against a stopper ring 5. There are also shown a return spring 6 for causing the piston 4 to return upon disengaging the clutch, a canceller seat 7, a stopper ring 8 for the canceller seat 7, a bearing 9 for a shaft 40, a central axis 50 of the shaft 40, a left oilway 35 formed for the piston 4 through an inner circumferential wall of the clutch case 3, and an oilway 41 also formed for the piston 4 through the shaft 40.
A clutch case is made of aluminum to reduce its weight. As is appreciated from the drawing, however, the clutch case 3 is kept around its piston oilway 35 in sliding contact with sealing members 42 arranged on the shaft 40. It is, therefore, necessary to surely provide the clutch case 3 with abrasion resistance. A sleeve 20 of a non-aluminum metal is, hence, press fitted in and fixed on the inner circumferential wall of the clutch case 3.
However, the non-aluminum metal and aluminum are different in the coefficient of linear thermal expansion. In an actual use environment, the temperature varies. As a consequence, individual parts of the clutch undergo expansion. The aluminum clutch case and the non-aluminum sleeve are different in the degree of expansion, so that the sleeve may become loose relative to the clutch case although the sleeve was press fitted. As a result, the sleeve may slide relative to the clutch case and an oilway 21 of the sleeve 20 and the oilway 35 of the clutch case 3 may become out of registration, leading to occurrence of a problem that pressure oil would no longer be supplied for the actuation of the piston.
It is, therefore, necessary to fix the clutch case and the sleeve with each other such that despite a difference in expansion between them upon occurrence of a temperature variation, the sleeve does not slide relative to the clutch case to avoid occurrence of any positional non-registration between their oilways.
In one aspect of the present invention, there is thus provided a multiplate clutch provided with a clutch case and a sleeve fitted in an inner circumferential wall of the clutch case with their piston oilways registered with each other, wherein:
the sleeve is provided in an outer circumference thereof with at least one notch; and
the inner circumferential wall of the clutch case has been crimped at a portion thereof into the notch such that a crimped portion is formed to fixedly secure the sleeve on the inner circumferential wall of the clutch case.
As the multiplate clutch according to the present invention is constructed as described above, the clutch case and the sleeve are fixed together by crimping. Even when a difference arises in expansion between the clutch case and the sleeve due to a difference in material therebetween at an elevated temperature, their engagement does not become loose so that no sliding takes place between them. It is, therefore, possible to prevent their oilways, which are arranged to supply pressure oil to actuate a piston, from becoming out of registration.